On my shed my sheathing does not protrude actually how both my house and shed are done is a 1 x 6 house 1 x4 shed fascia is installed to end of rafters then 1 x 1 1 2 is tacked onto the fascia at the top.
Roof sheathing does not overlap fascia board.
If the gutter is not secured snugly against the fascia or if the gutter was installed atop rather than under the drip edge you ll get this problem.
This opens the door to the possibility of water damage by letting gravity work against you.
Smooth the caulk bead with your finger and begin caulking the joint between the fascia board and the soffit also.
If the gutter is lower than the bottom edge of the drip edge install flashing behind the drip edge and over the back edge of the gutter to remove the gap.
Take a small scrap of the sheathing and a 2 piece of the facia from ur ladder hold the sheathing on the roof and slide it down to where the bottom edge of the sheathing is flush with the edge.
When sheathing a roof the first step is to snap a line so that the first row goes on straight.
On roofs with no eaves overhang or soffit proper installation of drip edge proud of the fascia board at the wall top is very important to avoid water damage to the building walls below.
In this video i trim my truss tails by snapping a chalk line drawing a plumb line down from that line and then using a circular saw to cut them off.
But if you snap it at 40 inches then the sheathing will not project over the subfascia or true fascia.
This is a known issue that is directly caused by capping over the fascia instead of doing a proper job and replacing it.
If the overlap is too short fix it by placing drip edge under the first row of roof shingles and be sure that the exterior edge is reaching over the gutter.
Start at the end of a fascia board and caulk the corner edge where two boards meet.
The roof sheathing comes down and ends on top of the 1 x fascia.